Method of manufacturing and use of combustible insert sleeves in the body of solid fuel heaters



3,475,531 NSERT Oct. 28, 1969 RODEN METHOD OF MANUFACTURING AND USE OF COMBUSTIBLB I SLEEVES IN THE BODY OF somn FUEL HEATERS.

Filed Jan. 18, 1968 71%.1. [Wm/e ART/ United States Patent "ice Int. Cl. B32b 31/06; C] 11/00," A01g 13/06 US. Cl. 264-262 2 Claims ABSTRACT OF THE DISCLOSURE A solid fuel heater which includes a container substantially filled with a solid fuel, having a combustible insert sleeve embedded therewithin with the top edge of the insert sleeve extending above the surface of the solid fuel to provide a reservoir of molten fuel after the heater has been ignited and is burning.

BACKGROUND OF THE INVENTION Field of the invention The present invention is directed to a solid fuel heater with non-extinguishing flame characteristics which is adapted particularly for use as an orchard heater. Included is a combustible insert sleeve which controls the setting of the fuel during cooling, and also serves as a retainer for molten fuel after ignition of the heater.

DESCRIPTION OF THE PRIOR ART In the coassigned patent issued to E. C. Knowles and F. C. McCoy on Aug. 29, 1967, Patent No. 3,338,691, for a Heating Composition, the disclosure of which is incorporated herein by this reference, there is disclosed and claimed, novel heating compositions and methods of making the same, and the methods of using such compositions.

Solid fuel heaters such as disclosed in this patent, are desirable for use in orchards to protect citrus trees from freezing. However, these heaters, due to their size, their use of solid fuel, and the heat they give off with low flame height, may be used in many other ways, such as camp stoves, personal heaters, emergency signals and the like.

Previously, citrus orchard heaters were in the shape of a rectangular box or upright cylinder and set in an open ended container. Embedded in the heaters were inserts which acted as flame holders during burning to sustain the burning during high winds. Further, hydrocarbon anaterials were impregnated in the fuel and inserts to aid in supporting combustion.

During fabrication of the heaters, molten fuel is poured into a container wherein it cools and contracts. A wicking means, e.g. oiled perlite, can be added either before or after the pouring. Due to the thermal gradient existing throughout the fuel during cooling, a separation results between the container wall and the cooled contracted solid fuel of the heater. Another void or vug is formed in the upper central portion of the solidified fuel below the wicking means.

When the solid fuel heater is ignited in the field, the fuel closest to the flame melts and floats on top of the still solid fuel. It is desirable that this molten fuel remain on the top of the heater in contact with the wicking means to feed the flame. Instead, the melted fuel would drain into the side wall separation or the central vugs or voids which form during the cooling, starving the flame. Thus, the heaters would have to be reignited continuously by an operator if the orchard was to be protected.

3,475,531 Patented Oct. 28, 1969 With one heater for each tree in an orchard,'reignition of the heaters can be a continuous and inconvenient task.

SUMMARY OF THE INVENTION An overall object of the present invention is to provide a solid fuel heater with an insert sleeve therein which acts as a reservoir for molten fuel.

A further object of the present invention is to provide a solid fuel heater capable of burning at a substantially consistent rate, due to the absence of voids or vugs therein.

Accordingly, in an embodiment of the present invention, there is included in a solid fuel heater comprising a container, a solid fuel within the container and a wicking means, a combustible insert sleeve which is set in the solid fuel so that the top edge of this insert extends above the surface of the solid fuel.

In fabricating the solid fuel heaters, a wicking means such as a scoop of oiled perlite is placed into a container followed by a molten fuel composition. The insert sleeve is embedded in the fuel before it solidifies completely.

BRIEF DESCRIPTION OF THE DRAWING FIG; 1 is an elevation cross section of a solid fuel heater as manufactured in the prior art; and

FIG. 2 is an elevation cross section of a solid fuel heater with an insert sleeve.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference is made to the figures of the drawing wherein a container 2 is shown as substantially filled with a solid fuel 4. In the prior art (FIG. 1), as the molten fuel cooled, it hardened irregularly to enclose a void or vug -6 in the upper central portion below wicking means 10 for the solid fuel 4.

The contraction of the fuel during cooling develops a separation or void 8 from the inside wall of the container 2 and is shown exaggeratedly.

Thus, when the heater was ignited, the molten fuel drained away from the combustion area into vugs, voids or separations, so that the flame, with little or no fuel, burned weakly before going out.

The solid fuel has the same composition as disclosed in the coassigned patent viz. to 99.9% of a wax component containing from 0.1 to 10% by weight of a buoyant particulate material component in contact with said wax to increase the burning rate of said composition, the buoyant material being selected from the group consisting of expanded vermiculite, shredded cork, perlite, pumice, hollow glass spheres having an average diameter of about microns, perlite-vermiculite, perlite-cork and perlite-pumice mixtures.

The solid fuel heater can be ignited readily by pouring a small amount of a lighter fluid over the wicking means at the top of the container. As the heater burns, the solid fuel 4 adjacent the flame melts and through the capillary action of the wicking means is fed to the flame.

FIG. 2 shows a solid fuel heater fabricated according to the present invention. An insert sleeve 12 is located generally centrally over the top of the already poured molten fuel so that the axis of the sleeve and container are generally aligned. While the fuel is partially congealed and still soft enough to penetrate the sleeve is forced into the fuel until it extends slightly above the top of the wicking means.

This insert sleeve serves two functions. As the fuel cools and solidifies, it does not adhere to the insert but slips down into the body of the fuel. Thus, formation of the vug 6 is averted in the solidified fuel in the container. Also, the projection of the insert sleeve is increased slightly above the top surface of the solid fuel 4 (be- 3 tween and A), so that it acts as a well to hold both the initial igniting fluid and later the molten fuel itself, preventing either from running into the void 8 along the inside wall of the container.

Although the insert sleeve 12 may be formed in any geometric cross-sectional shape, the circular configuration or cylinder is the more desirable, since it is easily fabricated. Since the sleeve 12 is combustible, it acts additionally as a secondary wicking means to aid in the buming of the heater especially during adverse conditions such as high winds. It has been found that the diameter of the cylindrical insert sleeve should be from /2 to that of the diameter of container.

Thus, there has been shown and described an insert sleeve for a thermal candle which averts the formation of vugs in the solidified fuel and acts as a well to contain lighting fluid for ignition as well as fuel melted by the flame.

It is obvious, of course, that variations may be made in the geometry of the insert sleeve, without departing from the essential attributes of the invention.

I claim:

1. In a method of fabricating a solid fuel heater, the steps comprising (a) positioning an open top container in an upright attitude;

(b) supplying said container with a wicking means;

(c) filling said container with molten fuel to below the top edge of said container;

(d) inserting a cylindrical sleeve insert in said fuel While it is in a partly congealed state and thru voids formed therein; and

(e) cooling said fuel to a solid state and allowing said fuel in the filled container to slip down and compact itself during said cooling.

2. A method as defined in claim 1 wherein said fuel comprises from 0.1 to 10% by weight of a buoyant particulate material component.

References Cited UNITED STATES PATENTS 2,168,698 8/1939 Bunt et al 43 l291 2,354,343 7/1944 Webber et al. 431289 3,338,691 8/1967 Knowles et al. 3,367,758 2/1968 Ambrose et al 431291 X FOREIGN PATENTS 661,222 4/ 1963 Canada.

CHARLES J. MYHRE, Primary Examiner US. Cl. X.R. 

